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authorYu Kuai <yukuai3@huawei.com>2022-11-15 22:10:52 +0800
committerJens Axboe <axboe@kernel.dk>2022-11-16 15:19:56 -0700
commit62f535e1f061b4c2cc76061b6b59af9f9335ee34 (patch)
tree32c2a4bf133cd6831d6226656969d6eefbe16c11 /block/holder.c
parent7abc077788363ac7194aefd355306f8e974feff7 (diff)
block: fix use after free for bd_holder_dir
Currently, the caller of bd_link_disk_holer() get 'bdev' by blkdev_get_by_dev(), which will look up 'bdev' by inode number 'dev'. Howerver, it's possible that del_gendisk() can be called currently, and 'bd_holder_dir' can be freed before bd_link_disk_holer() access it, thus use after free is triggered. t1: t2: bdev = blkdev_get_by_dev del_gendisk kobject_put(bd_holder_dir) kobject_free() bd_link_disk_holder Fix the problem by checking disk is still live and grabbing a reference to 'bd_holder_dir' first in bd_link_disk_holder(). Signed-off-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20221115141054.1051801-9-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/holder.c')
-rw-r--r--block/holder.c21
1 files changed, 15 insertions, 6 deletions
diff --git a/block/holder.c b/block/holder.c
index dd9327b43ce0..c8e462053f49 100644
--- a/block/holder.c
+++ b/block/holder.c
@@ -65,12 +65,24 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
if (WARN_ON_ONCE(!disk->slave_dir))
return -EINVAL;
- mutex_lock(&disk->open_mutex);
+ /*
+ * del_gendisk drops the initial reference to bd_holder_dir, so we
+ * need to keep our own here to allow for cleanup past that point.
+ */
+ mutex_lock(&bdev->bd_disk->open_mutex);
+ if (!disk_live(bdev->bd_disk)) {
+ mutex_unlock(&bdev->bd_disk->open_mutex);
+ return -ENODEV;
+ }
+ kobject_get(bdev->bd_holder_dir);
+ mutex_unlock(&bdev->bd_disk->open_mutex);
+ mutex_lock(&disk->open_mutex);
WARN_ON_ONCE(!bdev->bd_holder);
holder = bd_find_holder_disk(bdev, disk);
if (holder) {
+ kobject_put(bdev->bd_holder_dir);
holder->refcnt++;
goto out_unlock;
}
@@ -92,11 +104,6 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
goto out_del_symlink;
list_add(&holder->list, &disk->slave_bdevs);
- /*
- * del_gendisk drops the initial reference to bd_holder_dir, so we need
- * to keep our own here to allow for cleanup past that point.
- */
- kobject_get(bdev->bd_holder_dir);
mutex_unlock(&disk->open_mutex);
return 0;
@@ -106,6 +113,8 @@ out_free_holder:
kfree(holder);
out_unlock:
mutex_unlock(&disk->open_mutex);
+ if (ret)
+ kobject_put(bdev->bd_holder_dir);
return ret;
}
EXPORT_SYMBOL_GPL(bd_link_disk_holder);